Field of the Invention
The present invention relates to a method of forming a PNbZT ferroelectric thin film. Specifically, the invention relates to a method of forming a PNbZT ferroelectric thin film, which is used for a dielectric layer or the like of a thin film capacitor, using a sol-gel method. More specifically, the invention relates to a method of forming a PNbZT ferroelectric thin film in which a PZT ferroelectric thin film is doped with a high concentration of Nb to significantly improve ferroelectric properties such as relative dielectric constant without being doped together (hereinafter, referred to as “co-doping”) with silicon or the like.
Priority is claimed on Japanese Patent Application No. 2013-063179, filed on Mar. 26, 2013, the content of which is incorporated herein by reference.
Description of Related Art
When a PZT-based ferroelectric thin film formed of a perovskite type oxide such as lead zirconate titanate (hereinafter, referred to as “PZT”) is formed using a chemical solution deposition (CSD) method such as a sol-gel method, a technique of doping a PZT-based ferroelectric film with a donor atom other than metal elements such as Pb, which are major components of the film, to improve ferroelectric properties such as relative dielectric constant is known in the related art (for example, refer to Jian Zhong et al. “Effect of Nb Doping on Highly {100}-Textured PZT Films Grown on CSD-Prepared PbTiO3 Seed Layers”, Integrated Ferroelectrics). Specifically, for example, among Pb atoms, Ti atoms, Zr atoms, and the like constituting a PZT-based ferroelectric thin film, a method of substituting a part of Pb atoms of A site with trivalent lanthanum or bismuth or a method of substituting a part of Ti atoms or Zr atoms of B site with pentavalent Nb (niobium) or W (tungsten) is used. For example, PLZT obtained by adding a small amount of lanthanum to PZT can be obtained using the above-described method. As a technique of the related art using the above-described method, for example, a capacitor in which a dielectric film represented by the formula Pb(ZrxTiyMz)O3 (wherein M represents at least one selected from the group consisting of Nb, Ta and V, and x+y+z=1) is used as a dielectric layer; and a method of manufacturing the capacitor are disclosed (for example, refer to Japanese Unexamined Patent Application, First Publication No. 2005-72474 (claims 1 to 4, paragraphs [0008] and [1061])). That is, in the method disclosed in Japanese Unexamined Patent Application, First Publication No. 2005-72474, a ferroelectric film is formed by doping Nb atoms, Ta atoms, or V atoms.